The present invention is directed to scanning type projectors two-dimensionally scanning a laser beam and displaying an image, and relates to the configuration of optical elements that output a laser beam for providing a high resolution image.
In recent years, due to an increase in the output power and a reduction in the price of a visible light semiconductor laser, a scanning type projector has been realized, which two-dimensionally scans a laser beam emitted from a semiconductor laser onto a plane to be projected and displays an image. Because this scanning type projector directly modulates the light intensity of a laser beam and displays an image, it has an advantage in that the contrast ratio is extremely high as compared with the projectors using a conventional liquid crystal panel or the like. Furthermore, different from a liquid crystal panel and/or a projector using a digital mirror device (DMD) as an image modulation element, the scanning type projector directly modulates the light intensity of a laser beam and displays an image, so it has a high energy efficiency of projected light and thus is expected as the next-generation display device.
For example, JP-A-2010-32797 discloses one example of the technique for a light-scanning type projector. Specifically, JP-A-2010-32797 discloses a light-scanning type projector comprising; a light source unit emitting each of R, G, and B light beams; two wedge prisms substantially equalizing the luminous beam diameters of the light beams emitted from the light sources; a color synthesis unit coaxially synthesizing light beams from a plurality of light sources; a beam scanning unit two-dimensionally deflecting synthetic light; and a free curved face prism enlarging the deflection angle of the deflected synthetic light and projecting the resulting light.